In virtual currency activities, how to safely 'withdraw funds' is an enduring topic. U-cards seem to provide a convenient way to consume without the need to withdraw funds (which can also be seen as using U-cards being the safest way to withdraw), thus they are popular among cryptocurrency enthusiasts.
Many people have started the business of promoting U-cards. I often see advertisements for card issuance discounts in communities and platforms, and frequently on mainland video platforms, content is presented under the guise of popularizing U-card knowledge, which in fact encourages you to add private messages to purchase card issuance services. It is unclear whether these promoters are merely receiving commissions from the issuer or earning service fees from cardholders.